US3753703A - Sintered molybdenum boron alloy - Google Patents
Sintered molybdenum boron alloy Download PDFInfo
- Publication number
- US3753703A US3753703A US00865682A US3753703DA US3753703A US 3753703 A US3753703 A US 3753703A US 00865682 A US00865682 A US 00865682A US 3753703D A US3753703D A US 3753703DA US 3753703 A US3753703 A US 3753703A
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- US
- United States
- Prior art keywords
- boron
- molybdenum
- powder
- percent
- weight
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/04—Making non-ferrous alloys by powder metallurgy
- C22C1/045—Alloys based on refractory metals
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C27/00—Alloys based on rhenium or a refractory metal not mentioned in groups C22C14/00 or C22C16/00
- C22C27/04—Alloys based on tungsten or molybdenum
Definitions
- molybdenum-boron alloys can be produced to have properties better than molybdenum alone in that they have higher recrystallization temperatures without loss in ductility even in the recrystallized condition.
- the alloys of this invention exhibit a fine grain structure and as a result, the alloys remain ductile down to temperatures at least as low as 60 C. Nevertheless, the alloys in accordance with this invention have greater tensile strength than unalloyed sintered molybdenum.
- the alloys of this invention are made in accordance with powder metallurgical techniques. It is important, however, that the boron content of the alloy be kept very low.
- the boron content of the alloy will be from about 0.002 to 0.2 weight per cent, preferably less than about 0.01 per cent, generally from about 0.005 to 0.01 weight per cent.
- the alloy should contain less than about 0.0025 weight per cent of oxygen.
- the alloy contain a small quantity of tungsten in the range of 0.03 to 0.07 percent by weight, with the tungsten content preferably being about 0.05 percent.
- a further improvement in the physical properties of the alloys of this invention can be achieved by the optional addition of one or more of zirconium and hafnium in small amounts. Generally, the presence of a total of from about 0.05 to 2 percent by weight of zirconium and hafnium will be effective.
- the alloys of this invention are prepared by powder metallurgical techniques which involves the mixing together of the metallic powders, compression to form a compact of the desired shape followed by sintering and cooling.
- the starting metallic powders that are employed should each have a very small oxygen content in order to insure a low oxygen content in the final alloy.
- the oxygen content of the starting powders should not exceed about-350 parts per million.
- the molybdenum powder. should preferably have a particle size within the range of about 2 to 7 microns. Smallquantities of impurities that do not affect the basic physical properties of the molybdenum itself in the quantities present can be employed but the total impurities should not exceed about 0.2 percent.
- the boron powder should also preferably have a particle size of from about 2 to 7 microns and it is preferred that the boron be added to the powder mixture in the form of molybdenum boride powder rather than in the form of elemental boron.
- Elemental boron can, however, be used as a less desirable alternative if it is substantially free of interfering impurities.
- molybdenum boride powder is used as the source of the boron, the molybdenum portion of the molybdenum boride will contribute to the over-all content of molybdenum in the alloy and calculations must be made accordingly.
- Some or all of the boron can also be added in the form of other metallic borides in which the metallic component is present in small quantity and does not interfere with the results obtained.
- the properties of the alloy depend on the actual boron content of the end product and not on the boron content of the charged powder.
- the actual quantity of boron or boron-containing powder to be added and mixed with the molybdenum powder to obtain a predetermined boron content in the alloy will necessarily have to be determined by trial but the trial will be aided by knowledge of the oxygen content of the powders and a rough calculation of the ap proximate quantity of boron oxides that would be expected to be vaporized.
- tungsten powder would also be added to the powder mixture and the tungsten powder would also have a particle size preferably within the range of about 2 to about 7 microns and again would be relatively pure and not contain any impurities in quantities sufficient to interfere with the properties of the finished alloy.
- Tungsten can also be added in the form of a molybdenum-tungsten alloy or mixture Similarly, if zirconium and hafnium are to be added, they can be added in the form of metallic powders but more preferably they are added in the form of zirconium hydride and hafnium hydride powders, respectively. These components would each have a particle size within the range of from about 10 to about 20 microns, preferably having an average particle size of about 15 microns.
- Any conventional technique can be used to mix the. powders together such as, for example, ball milling, or
- the powder mixture is compressed into a compact of the desired shape such as, a rod or bar or particular finished article.
- the sintering pressure should be in the order of about 4 to 6 tons per square centimeter.
- the compression can be under ambient temperature conditions.
- the compacted articles are sintered at an elevated temperature within the range of about l,800 to 2,100 C., preferably 1,900 to 2,000 C.
- the sintering takes place in a protective atmosphere to prevent oxide formation within the alloy.
- the protective atmosphere can be an atmosphere of an inert gas such as helium or argon or the like, or it can be a reducing atmosphere such asan atmosphere of hydrogen.
- sintering can take place in a protective atmosphere that is substantially evacuated by im: position of strong vacuum. Where vacuum sintering is employed, the minimum vacuum during sintering should be in the range of 10 to 10' mm of mercury.
- Sintering should take place for a period of time sufficient to achieve adequate alloy fonnation and exact time of sintering will depend on the temperature employed, the thickness of the compact and the exact composition of the mixture. Preferably, a sintering time of from about 2 to 4 hours will suffice. Depending upon the end use desired, the optimum parameters of time and temperature of sintering that are particularly desirable in any given instance can'easily be determined by trial. After sintering has taken place, the sintered alloy should be allowed to cool to room temperature while remaining in a protective atmosphere.
- Alloys of this invention containing zirconium and/or hafnium can also be further heat treated by precipitation hardening in accordance with conventional techniques.
- the mechanical properties of such alloys, particularly their hot strength, can be greatly increased in this manner.
- Precipitation hardening is preferably achieved by annealing at the temperature in the order of about 1,800 C. followed by quenching to about l,l00 C. and holding at this temperature. This produces coherent precipitates of complex zirconium and- /or hafnium-containing molybdenum phases.
- the heat treatment requires about 50 to I00 hours.
- the molybdenum alloys of this invention whether or not they contain zirconium and/or hafnium as additives are characterized by particular ease of deformation.
- recrystallized sheet can be slightly deepdrawn and subjected to other non-machining types of deformation.
- the alloys of this invention find particular use in the blades of helium gas turbines of atomic reactor power installations. This utility is possible because of the high creep strength of the alloys.
- other utilities for the alloys can be found based upon their good weldability. They can be joined efficiently by electron beam, spot welding or pressure welding. Thus, they can be used in chemical apparatus and as structural parts of electron tubes.
- EXAMPLE I A molybdenum powder prepared by reduction and having an average particle size of 5 microns and a specific surface area of 0.2 square meters per gram was employed. This molybdenum powder also had as impurities 60 ppm iron, 30 ppm silicon, 500 ppm tungsten, 100 ppm carbon and 300 ppm oxygen. 1 gram of molybdenum boride were added and mixed with the molybdenum powder, the molybdenum boride having an average particle size of microns. The powder was mixed to fonn an intimate mixture and then pressed into bars at a pressure of 5 tons per square centimeter. The pressed bars were then sintered for 2 hours at 2,000 C. in an atmosphere of hydrogen gas. Following sintering, the bars were allowed to cool to room temperature in the hydrogen atmosphere.
- the boron content of the finished alloy was found to be within the range of 50 to 75 parts per million, i.e., in the range of about 0.005 to 0.007 weight per cent.
- FIG. 1 shows the elongation displayed by the various sintered and recrystallized bars having different boron additions.
- FIG. 2 shows the tensile strength in kilograms per square millimeter. Each is shown at varying temperatures within the range of 60 to C.
- the alloys of this invention despite their excellent ductility, have a much greater strength than the boron-free alloys and those alloys having less than 0.01 percent by weight of boron are particularly advantageous. This shows that the very small quantities of boron content in the alloys of this invention impart a very substantial benefit to the molybdenum and a more substantial benefit than, in fact, higher amounts of boron.
- Example 2 The procedure of Example I was followed except that to the powder mixture of molybdenum and molybdenum boride, I percent of hafnium was added in the form of hafnium hydride with mixing and compression into bars at a pressure of 5 tons per square centimeter. The bars were then sintered in hydrogen at 2,l00 C. for 4 hours and then allowed to cool in hydrogen in the furnace. The bars were then annealed for 2 hours at l,800 C. in hydrogen, rapidly cooled, and then again annealed for 50 hours in hydrogen at 1,l00 C. Bars of excellent physical properties were achieved.
- Example 3 The method of Example I was followed except that in addition to molybdenum and molybdenum boride, additions were made of zirconium hydride and hafnium hydride in powder quantities sufficient to yield 0.5 percent zirconium by weight and 1.5 percent hafnium by weight. All other conditions are the same as in Example I except, in order to attain adequate diffusion of the additions into the base metal, the sintering time was extended for a period of 6 hours.
- a method of producing a sintered molybdenumboron alloy which has high ductility at low temperature and which contains from about 0.002 to 0.2 percent by weight of boron, which comprises mixing the powdered constituents, compressing the resultant mixture to form a compact, sintering the compact at a sintering temperature for a period of time necessary to achieve sintering and cooling in a protective atmosphere, the improvement which comprises employing molybdenum boride as the source of boron.
- the improvement which consists essentially of employing molybdenum boride as the source of boron.
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Powder Metallurgy (AREA)
- Ceramic Products (AREA)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT993368A AT285966B (de) | 1968-10-11 | 1968-10-11 | Gesinterte Molybdän-Bor-Legierung |
Publications (1)
Publication Number | Publication Date |
---|---|
US3753703A true US3753703A (en) | 1973-08-21 |
Family
ID=3618560
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US00865682A Expired - Lifetime US3753703A (en) | 1968-10-11 | 1969-10-13 | Sintered molybdenum boron alloy |
Country Status (5)
Country | Link |
---|---|
US (1) | US3753703A (de) |
AT (1) | AT285966B (de) |
DE (1) | DE1950260C3 (de) |
FR (1) | FR2020407A1 (de) |
GB (1) | GB1249404A (de) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3977838A (en) * | 1973-06-11 | 1976-08-31 | Toyota Jidosha Kogyo Kabushiki Kaisha | Anti-wear ferrous sintered alloy |
WO2019060932A1 (de) | 2017-09-29 | 2019-04-04 | Plansee Se | Molybdän-sinterteil |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4755712A (en) * | 1986-12-09 | 1988-07-05 | North American Philips Corp. | Molybdenum base alloy and lead-in wire made therefrom |
CN110218927B (zh) * | 2019-07-17 | 2021-02-12 | 山东省机械设计研究院 | 一种高温硬质合金及其制造方法 |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1648679A (en) * | 1921-01-18 | 1927-11-08 | Gen Electric | Incandescent lamp |
US2793951A (en) * | 1953-06-19 | 1957-05-28 | Gen Electric Co Ltd | Powder metallurgical process for producing dense tungsten alloys |
-
1968
- 1968-10-11 AT AT993368A patent/AT285966B/de not_active IP Right Cessation
-
1969
- 1969-10-06 DE DE1950260A patent/DE1950260C3/de not_active Expired
- 1969-10-10 FR FR6934696A patent/FR2020407A1/fr not_active Withdrawn
- 1969-10-13 GB GB50150/69A patent/GB1249404A/en not_active Expired
- 1969-10-13 US US00865682A patent/US3753703A/en not_active Expired - Lifetime
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1648679A (en) * | 1921-01-18 | 1927-11-08 | Gen Electric | Incandescent lamp |
US2793951A (en) * | 1953-06-19 | 1957-05-28 | Gen Electric Co Ltd | Powder metallurgical process for producing dense tungsten alloys |
Non-Patent Citations (2)
Title |
---|
First Quarterly Report on Investigation of Molybdenum and Molybdenum Base Alloys Made by Powder Metallurgy; Bruckart et al., pp. 6 8 and 22 23 * |
Jaffee, R. I., Chapter 15, pg. 330 354 in The Metal Molybdenum; American Society for Metals, 1956 * |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3977838A (en) * | 1973-06-11 | 1976-08-31 | Toyota Jidosha Kogyo Kabushiki Kaisha | Anti-wear ferrous sintered alloy |
WO2019060932A1 (de) | 2017-09-29 | 2019-04-04 | Plansee Se | Molybdän-sinterteil |
US20200306832A1 (en) * | 2017-09-29 | 2020-10-01 | Plansee Se | Sintered molybdenum part |
JP2020535318A (ja) * | 2017-09-29 | 2020-12-03 | プランゼー エスエー | モリブデン焼結部品 |
JP7273808B2 (ja) | 2017-09-29 | 2023-05-15 | プランゼー エスエー | モリブデン焼結部品 |
US11925984B2 (en) * | 2017-09-29 | 2024-03-12 | Plansee Se | Sintered molybdenum part |
Also Published As
Publication number | Publication date |
---|---|
GB1249404A (en) | 1971-10-13 |
FR2020407A1 (de) | 1970-07-10 |
DE1950260C3 (de) | 1979-03-15 |
DE1950260B2 (de) | 1978-07-13 |
DE1950260A1 (de) | 1970-08-27 |
AT285966B (de) | 1970-11-25 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: SCHWARZKOPF TECHNOLOGIES CORPORATION, A CORP. OF M Free format text: CHANGE OF NAME;ASSIGNOR:SCHWARZKOPF DEVELOPMENT CORPORATION, A CORP. OF MD;REEL/FRAME:005931/0448 Effective date: 19910517 |